pgsql: Doc: fix misleading syntax synopses for targetlists.

Doc: fix misleading syntax synopses for targetlists.

In the syntax synopses for SELECT, INSERT, UPDATE, etc,
SELECT ... and RETURNING ... targetlists were missing { ... }
braces around an OR (|) operator.  That allows misinterpretation
which could lead to confusion.

David G. Johnston, per gripe from masondeanm@aol.com.

Discussion: https://postgr.es/m/172193970148.915373.2403176471224676074@wrigleys.postgresql.org

Branch
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REL_12_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/551ea63aaa2d6f63f167f273926ca6d2f8c6f9ac

Modified Files
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doc/src/sgml/ref/delete.sgml      | 2 +-
doc/src/sgml/ref/insert.sgml      | 2 +-
doc/src/sgml/ref/select.sgml      | 2 +-
doc/src/sgml/ref/select_into.sgml | 2 +-
doc/src/sgml/ref/update.sgml      | 2 +-
5 files changed, 5 insertions(+), 5 deletions(-)